(1) Field of the Invention
This invention relates to an outflow prevention device, and more particularly to an outflow prevention device for preventing a refrigerant within an automotive air conditioner from flowing out into a vehicle compartment.
(2) Description of the Related Art
In automotive air conditioners, CFC-based refrigerants are used as refrigerant for a refrigeration cycle. However, in view of a global environmental problem that chlorofluorocarbons destroy the ozone layer, causing danger of ultraviolet rays harmful to human health radiating through ozone holes onto an earth surface, CFC substitutes as refrigerants are being studied.
In recent years, a refrigeration cycle using carbon dioxide as a refrigerant has been drawing attention. The refrigeration cycle using carbon dioxide is basically constituted by devices similar to ones used in a refrigeration cycle using a CFC refrigerant.
More specifically, a refrigeration cycle is comprised of a compressor for pressurizing refrigerant up to a supercritical region, a gas cooler for cooling the pressurized refrigerant by heat exchange with the outside air, an expansion device for depressurizing the refrigerant delivered from the gas cooler, and an evaporator for evaporating the depressurized refrigerant by heat exchange with air in a vehicle compartment. Further, in the refrigeration cycle using carbon dioxide as a refrigerant, at respective locations downstream of the evaporator, there are arranged an accumulator for storing excess refrigerant, and an internal heat exchanger for cooling the refrigerant cooled by the gas cooler, by refrigerant being sent to the compressor from the accumulator.
The compressor, the gas cooler, the expansion device, the accumulator, and the internal heat exchanger, which form the refrigeration cycle, are arranged in an engine room, while the evaporator is arranged in the vehicle compartment. During cooling operation, when refrigerant having become a low-temperature refrigerant by being depressurized in the expansion device is supplied to the evaporator, the evaporator exchanges heat with the air in the vehicle compartment to thereby cool the air.
In the refrigeration cycle using carbon dioxide as a refrigerant, pressure is much higher than in a refrigeration cycle using a CFC-based refrigerant, and hence component parts used therein are highly pressure-resistant.
However, in the evaporator arranged as a heat exchanger in the vehicle compartment, rupture or outflow can occur despite of the highly pressure-resistant design of the evaporator. If carbon dioxide flows out into the vehicle compartment, an oxygen deficiency occurs in the vehicle compartment, which can do harm to passengers.